1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to calibrating a position of an image sensor and detecting the position of an image sensor, and more particularly, to calibrating a position of an image sensor in order to improve the resolution and quality of an image obtained through the image sensor and detecting the position of an image sensor.
2. Description of the Related Art
An image sensor is an apparatus for obtaining one-dimensional or multi-dimensional digital image information from an image source. Image sensor types broadly include an image pickup tube and a solid-state imaging device. The image pickup tube is an electronic tube with a special shape emitting an electronic beam, and the solid-state imaging device is a device in which a photo sensing device and an emission circuit are integrated onto a semiconductor substrate.
The solid-state imaging device has been developed to replace the image pickup tube that is mainly used for televisions, and includes a metal oxide semiconductor (MOS) and a charge-coupled device (CCD).
Due to a recent trend in the market for apparatuses capable of photographing images, such as digital cameras, digital camcorders, mobile phones, and personal digital assistants (PDAs), the demand for high resolution and high quality images has increased.
A method of increasing the resolution or quality of an image sensor is accomplished by increasing the number of pixels. The size of the semiconductor device needed for a particular number of pixels also increases in proportion to the increase in the number of pixels, thereby increasing the cost and the size of the image sensor. If the size of a unit pixel is reduced and as such, the number of pixels is increased, the sensitivity of the pixels also decrease with the decrease in size of the pixels due to technological limitations.
In addition to the method of increasing the resolution or quality of an image sensor, a moving image sensor has been suggested in which the resolution or quality of an image is improved by moving the moving image sensor.
FIG. 1A illustrates a related art moving sensor in which a micro-lens array (MLA) 1, a color filter array 2, a metal opaque layer 3, a photodiode 4, a silicon substrate 5, and a scanner 6 are integrally formed.
FIG. 1B illustrates a related art structure of a moving image sensor in which a laminate consisting of the MLA 1, the color filter array 2, and the scanner 6 and a laminate consisting of the metal opaque layer 3, the photodiode 4, and the silicon substrate 5 are separated and the former laminate is moved.
FIG. 1C illustrates a related art structure of a moving image sensor in which a laminate consisting of the MLA 1, the color filter array 2, and a support unit 7 and a laminate consisting of the metal opaque layer 3, the photodiode 4, the scanner 6, and the silicon substrate 5 are separated and the latter laminate is moved.
In the moving image sensor illustrated in FIG. 1A through 1C, the image sensors should be moved accurately to a desired position in order to improve the resolution and quality of an image. For example, if a moving image sensor with a size of one-pixel is moved, the quality of the image sensor can be improved, and if a moving image sensor with a size of ½-pixel is moved, the resolution of the moving image sensor can be improved.
In the related art technology, in order to move an image sensor to a desired distance, a position sensor, such as an electrostatic capacitance sensor, is separately used. However, in order for the position sensor to be used, the position sensor must compensate for a position error due to thermal drift or aging of a driving apparatus for the position sensor. The position sensor does not exhibit linear characteristics, and is costly.
There are image sensors that do not use the position sensor method. Such image sensors use position-tracking algorithms, such as an intensity interpolation method, a correlation coefficient curve-fitting or interpolation method, a Newton-Raphson iteration method, a double Fourier transform method, and gradient-based methods. However, the related art methods involves complicated calculations for at least one of position tracking and calibrating of an image sensor.